<html>
	<head>
		<style>
			.box {
				width: 200px;
				height: 200px;
				margin-top: 100px;
				background: #f09;
				animation: bounce 2s linear 0s infinite alternate;
				background-image: linear-gradient(45deg, #3023AE 0%, #f09 100%);
			}

			@keyframes bounce {
				0% {
					border-radius: 40% 60% 72% 28% / 70% 77% 23% 30%;
				}

				100% {
					border-radius: 75% 25% 24% 76% / 13% 15% 85% 87%;
				}
			}
		</style>
	</head>
	<body>
		<div class="box"></div>
	</body>
	<script>
		// 计算斐波那契数列,这个数列从第3项开始，每一项都等于前两项之和。
		function recurFib(n) {
			if (n < 2) {
				return n;
			} else {
				return recurFib(n - 1) + recurFib(n - 2)
			}
		}

		window.onload = function() {
			setTimeout(function() {
				console.time("运算耗时：")
				// 计算n为40的结果
				console.log('结果：', recurFib(40))
				console.timeEnd("运算耗时：")
			}, 2000)
			document.getElementsByClassName("box")[0].addEventListener('click', function() {
				console.log('click')
			})
		}
	</script>
</html>